The present invention relates in general to bellows-type expansion joints and more particularly to a new and improved joint having means for preventing overextension in the event of pipeline anchor failure.
An expansion joint with which this invention is concerned is installed between and coupled to the end portions of two rigid pipes or conduits for the purpose of absorbing axial movement resulting from pipeline expansion and contraction and absorbing some lateral deflection thereof. Such joints include an expansible bellows comprising a relatively thin walled, circumferentially corrugated tubular member, and end portions adapted for connection to the corresponding axially aligned pipe end portions. When the expansion joint is installed between two pipe end portions, the bellows expands and contracts in response to axial movement of the pipes between which it is connected, and the joint is constructed such that the expected range of pipe movement will cause expansion of the bellows well within the movement capability of the bellows. Pipe movement beyond a certain limit causing joint overextension and consequently extension beyond the movement capability of the bellows may result in a bellows rupture and consequent failure of the joint. To prevent such overextension, pipeline anchors are provided on opposite sides of the joint to limit axial pipe movements. Also in some instances external restraint hardware may be provided on the joint itself. However, if one or more anchors or external restraints should happen to fail, control of the joint expansion or pipe movement is lost and the joint is exposed to possible overextension.